Web splicers are conventionally used to supply a continuous web of material, such as paper, plastic, woven materials and the like to a parent machine which demands an uninterrupted supply of material. Typically, a continuous and steady supply is needed to increase efficiency and reliability and to eliminate costly down time of the parent machine. It is known that web splicers are used in a variety of applications such as newspaper printing (where printing quality depends on a constant feed of paper at a constant linear speed), corrugated cardboard construction, container labeling, and in a variety of industries where high precision is demanded, where down time is costly or where web materials are used.
By way of example, where the parent machine is a container labeling system, a long web of material with container labels printed thereon in series is fed from the web splicer apparatus to the takeup system of the parent container labeling machine. The web is typically fed to a vacuum drum within the labeling machine where the web is severed into individual labels while on, or being delivered to, the vacuum drum. Thereafter, an adhesive material is applied to the labels and the labels are applied to containers, such as bottles or cans.
In conventional splicers the web material from a first expiring (or running) supply roll of web material is fed through a guidance mechanism, past a splicer unit, and through a festoon. The festoon typically contains a series of rollers through which the web is fed forming a sinusoidal path and is designed to collapse in order to dissipate the effects of an increase in tension upon the web. The festoon includes a moveable carriage, comprised of a plurality of spaced rollers, biased against the web tension so that a specified length of web material will be contained within the festoon at any given time. A second (or fresh) supply roll of web material is fed through a second series of guide rollers and held so that the leading portion is in close proximity to the running web. When the first expiring supply roll of the running web is near depletion, a splice can be made which affixes the leading portion of web material from the second source of supply to the web material of the running web. Typically, the two webs are affixed using double-face tape, that is, tape with contact adhesive on both sides. Thereafter, the remaining portion of the first supply web is severed so that web material from only the fresh source of supply will be fed to the takeup system of the parent container labeling machine.
In order to accomplish high speed splices, conventional splicers utilize a festoon system on the expiring web. When the splice is to be made, the festoon system collapses to provide a reservoir of material in the expiring web. The trailing portion of the reservoir material can be grasped and held at, or near, zero speed while the splice is completed. The remainder of the reservoir material can then be used to allow for controlled acceleration of the fresh supply roll. Alternatively, the expiring roll of material may be subjected to a braking action to slow down the speed of the running web. As the takeup system of the parent machine maintains a constant pulling force, the web material stored in the festoon is consumed. When the splice has been completed the festoon allows for controlled acceleration of the fresh supply roll of web material to operational speeds. Therefore, through utilization of the festoon system, conventional splicers are able to splice the slow moving or completely stopped running web without altering the linear speed at which the web material is fed to the parent machine.
When utilizing the festoon system, conventional splicers are able to decrease the linear speed of the expiring web in the vicinity of the splicer unit so that an accurate splice may be accomplished. When web splices are made at lower speeds, conventional splicers are able to splice the two webs with accurate registration. Typically, the leading portion of the second supply roll is joined together with the slow moving or stopped web of the first supply roll. The strength of the splice is sufficient to resist the sudden tension required to accelerate the new roll of material up to the existing linear speed of the expiring web.
Conventional splicers utilize various methods to aid in the acceleration of the fresh web. In particular, it is known that the web material may be "pulled" by the takeup system of the parent machine through the use of a set of driven pinch rollers which grasp the web from the top and the bottom of the sheet and through rotation pull the web up to operational speed. Similarly, many splicers "push" the fresh source of supply to speed by driving the fresh roll of web material itself. The driving is typically accomplished by an external motor which induces an acceleration on the roll of web material that is transmitted to the leading portion of the fresh web. Similarly, many known splicers utilize a combination of aids to accelerate the fresh supply roll up to operational speeds.
Prior art splicers are not capable of splicing web material with accurate registration when the running web is moving above a certain speed in the vicinity of the splicer unit. It is for this reason that conventional splicers utilize the above described festoon system. Accurate registration requires the splicer unit to press the leading portion of the web material from the fresh supply roll onto the running web at precisely the correct moment. Known splicers, however, are not able to press the rolls together quickly enough or at precisely the correct moment to insure accurate registration at high web speeds.
In general, known splicers are not able to perform accurate high speed splices because of the complex nature of the splicers themselves. Known splicers generally utilize a series of switches and relays to activate the cutting and pressing steps of the splicing operation. The cutting and pressing steps require separate motions and are found to be independent from each other in many prior art splicers thereby requiring complex relay and timing systems. Typically, the high number of subsystems and/or parts needed to accomplish these tasks in known splicers prevents accurate timing and therefore causes known splicers to provide inaccurate registration during high speed splicing.
The present invention is designed and intended to provide a solution to the above noted problems. It is therefore a broad object of the invention to provide an improved web splicing apparatus which is capable of splicing web material, moving at relatively high linear velocities, with accurate registration.
It is further an object of the present invention to provide accurate splicing of web material at relatively high speeds without utilizing a festoon or comparable system.
It is further an object of the present invention to provide accurate splicing in an apparatus that does not require a source of power, other than the pull of the takeup system of the parent machine itself, to feed a continuous web of material at a nearly constant linear speed to the parent machine.
Finally, it is an object of the present invention to provide an improved web splicing apparatus which is capable of providing accurate registration during web splicing by reducing the number of independently moving parts while insuring that the cutting and pressing steps involved in web splicing are mechanically dependent upon each other so that each web splice can occur at near instantaneous speeds.